JVM Options

The recommended way of changing the JVM options in the recent product versions is from the Help | Edit Custom VM Options menu. This action will create a copy of the .vmoptions file in the IDE config directory and open an editor where you can change them. If you can't start IDE to access this menu, edit the file manually as described below.

VM options are loaded from the IDE_HOME\bin\<product>[bits][.exe].vmoptions file or from the copy of this file in the config directory (if it exists). Please note that .vmoptions file from the config directory has the priority over the original file in the bin directory.

If you are running under 64-bit JVM (verify in Help | About), options should be edited in the file with 64 suffix in its name (idea64.exe.vmoptions, or idea64.vmoptions on Linux, but always idea.vmoptions on Mac).

product would be one of following: idea, phpstorm, webstorm, pycharm, rubymine, appcode.

-Xmx value limits the maximum heap memory size that the JVM can allocate.

In order for the customizations to survive updates, copy the file to IDE configuration directory, then modify the copy instead of the original.

Mac OS X Specifics

Don't edit .vmoptions and .properties files directly, it will violate the application signature, always make a copy of the files under IDE configuration directory and edit the copy instead. See this answer for details. The original file is located in /Applications/<Product>.app/Contents/bin folder (/Applications/<Product>.app/bin for older IDE versions).

IntelliJ IDEA Platform Properties

The recommended way of changing the platform properties in the recent product versions is from the Help | Edit Custom Properties menu. This action will create a copy of the .properties file in the IDE config directory and open an editor where you can change them. If you can't start IDE to access this menu, edit the file manually as described below.

You can change properties in the IDE_HOME\bin\idea.properties file for all the products, some popular properties that you may want to adjust:

#---------------------------------------------------------------------# Maximum file size (kilobytes) IDE should provide code assistance for.# The larger file is the slower its editor works and higher overall system memory requirements are# if code assistance is enabled. Remove this property or set to very large number if you need# code assistance for any files available regardless their size.#---------------------------------------------------------------------idea.max.intellisense.filesize=2500

#---------------------------------------------------------------------# This option controls console cyclic buffer: keeps the console output size not higher than the specified buffer size (Kb)# Older lines are deleted. In order to disable cycle buffer use idea.cycle.buffer.size=disabled#---------------------------------------------------------------------idea.cycle.buffer.size=1024

In order for the customizations to survive updates, copy the file to IDE configuration directory, then modify the copy instead of the original.

@Raul, the behavioural and performance settings are specifically combined to fit my machine and the type of projects I'm working with. Some of those flags are deprecated or changed with java 8... you can read more about the flags in the documentation:

@Todd I had the same problem and it was because I was trying to use the shortcut for the previous version. I just pinned the new shortcut that was created and now it works. Not sure if this is the same problem you are having.

For Mac OS X, **DO NOT** make your own copy of idea64.vmoptions. Simply use the Help-->Edit Custom VM Options. It will make the copy for you.

I had problems when I created idea64.vmoptions myself (per this article) and then used the Help menu to edit it. Everything saves OK, but my new VM Options were still not being used. I deleted the new idea64.vmoptions file and started again from scratch, and it seems to finally be working. I can finally use IntelliJ in "real time" again :-)